Great Planes Giant P6E Hawk--Electric Conversion

[Grover54]

Well, the Xoar props are just the best IMO. Highly precise, efficient, and come pre-balanced. Worth every penny IMO. But a less aggressive prop.... Believe me, they are not considering the aircraft. This airplane had LOADS of drag. You will want the 12"pitch to get out of trouble spots. Halving the pitch will increase your thrust, yes, but you will lose airspeed... a LOT of airspeed. You will be struggling to keep it in the air. I tried a 16x10 and it was marginal. The 18x12 will suck up some power to overcome the drag but that is expected. You have a rather large frontal area, a HUGE scoop on the bottom, two wings, and struts. Plenty of drag... even without the elastic cords. While a 18x8 would give you good thrust to overcome things, you would still be struggling with airspeed... which is what you need to keep flying.

Math lesson:
32Kv motor * 25.2V = 8064rpm

8064rpm * 8 inch prop pitch = 64512 in/min = 61mph
8064rpm * 12 inch prop pitch = 69768 in/min = 66mph

so, you can quibble over 5mph all you want but if you are hauling around a 14-pound airplane you better be darn sure you have the airspeed to do what you want to do.

Thanks Josh! This is exactly the information I needed. You are correct, I was doing a mental list of all the drag points on this bird and they do add up so I'll go ahead and stick with the 18X12

 

[Grover54]

Interesting.... I was surfing around looking for some historical information of the P-6E Hawk and found this link to the National Museum of the USAF.

If you haven't seen this before it's worth a watch. Lots of historical info and behind the scenes color told by the Curator. Most interesting is the particular model in the clip (the last P-6 in the world) has a 3-bladed prop? Never knew it used a three bladed prop, did you?

We have an awesome plane!

 

[willsonman]

I did, they tend to have more drag at our scale. For our electric setups, the 2-blade option is far more efficient too.

 

[Grover54]

In case you saw my dissertation and photos on the motor mount issues I "thought" I was having, I deleted that post since I worked it out. Just needed to put a bit more thought to it before getting you involved. Motor and ESC installed and functioning properly. I think I may actually be in the air this weekend as planned for her Maiden. Stay tuned.

 

[willsonman]

Flight report?

 

[Grover54]

Exciting News! Did the Maiden last Saturday and V.2 yesterday and she flew like an angel! Had some minor adjustments after the first flight but my V.2 was fantastic. What a beautiful bird and handles like a dream VERY STABLE! I must extend my thanks to you Josh for all you help and direction and to my training mentor Ron Luessen here in our Club. Here are a couple pics however, I'm having problems uploading videos. Tried all formats but it says they're not compatible with the "approved" Flight test formats? I'll upload videos when I figure out want the problem is.

 

[nhk750]

Beautiful bird, it really came out nice, congrats! Just upload your videos to YouTube and put a link here, much easier.

 

[willsonman]

About what I expected. She is a real peach and just does not have ANY bad habits.

 

[Grover54]

Updates on the beautiful P-6E Hawk I completed on 7/14/18. Flew like an Angel and even better the second flight after a few adjustments and tweaks.

What a bird!

\

One more

 

[Grover54]

Josh, Sorry it took so long but it's a big file to upload and I've had a lot of distractions the last several days. Here is the best shot of my Maiden for the P6E Hawk. Damn this is a beautiful Bird and a dream to fly. Thanks for watching!

My cameraman spent a bit too much time on me than my flight but he wanted to make sure my son was convinced I was the one flying.

 

[willsonman]

Yep, looks like she goes just like mine. So happy you are enjoying her!

 

[nhk750]

Looks great, nice flying plane.

 

[Grover54]

An unfortunate update on the HAWK. Hated to lose my "crash" virginity on this baby but I did. Everyone said it's part of the hobby and I'm told it's never easy even for the very experienced. What pizzzzes me off most is it was a STUPID mistake and clearly avoidable. I didn't realize I had as much elevator as I did because of focusing on a cross wind. It jumped in the air and stalled...… Well, the good news is the damage wasn't as bad as it looked and I'm confident I can get everything fixed. Obviously need a new prop, the fiberglass cowl took a major hit but it popped reasonably right back and with some fiber bond, sanding and paint I'm sure I can make it look new.

Most of my fellow pilots were amazed the damage was no more severe than it was. This bird is a structural tank but I'll certainly be more careful next time. Second chances are rare in this business.

 

[willsonman]

Wow, that is unfortunate. BUT, let the wound bleed out for a bit and then come back. Looks like you have all the pieces to put it back together.

 

[Grover54]

Yes, broke off about 4 - 5" of the upper left wing tip and a little damage to the trailing edge on the lower wing but most of the parts that came off seemed to separate in pieces at their connecting points. Very lucky. I'm told if you can retrieve your crash without using a "trash bag" it's always repairable. The only damage to the fuse is a horizontal support strip on the bottom edge below the pilot that looks like it just separated from the rib joint and can be re-glued. I was afraid I wouldn't be able to find the right color of MonoKote since this is a very old plane and spares no longer available but I found some. Stay tuned for when I get her out of the shop.

 

[nhk750]

Sorry to hear about the crash, I'm still not over crashing my Taylorcraft, as it's totaled. I still have it, but wing is shredded in half and the nose of the fuse was destroyed including the wing mounting area...sad face...

 

[Grover54]

This could be a crazy question but as a novice in repairing balsa damage I'm thinking it may be good to find scale plans of the wing to repair the 4 - 5" damage to the left upper wing tip and some damage to the lower wing's trailing edge. For the life of me I can't find any plans for this 76" wingspan scale. I did find plans for a giant 1/4 scale Hawk (94.5" wingspan) and inquired (3X) if they could scale it down to the 76" scale but never received a reply to my inquiries. I'm not opposed to trail and error but I want to do it right so I can get it back to it's original pristine condition. Any suggestions?

 

[rockyboy]

If you aren't able to find plans, you could also cut the covering off the opposite wing tip and use measurements from those parts to rebuild the boo-boo.

 

[willsonman]

That would be my recommendation as well. Plans are usually never offered for ARFs. It's a real drawback to making repairs and extending the life of a model. It's like they expect us to be perfect pilots every time in any circumstance! The Cub Yellow is still sold. Supply may be currently low everywhere with the Hobbico buyout but after talking with the HH reps at FF, it sounds like the monokote line will be continued. It's in stock at Tower so grab a roll for your current and future needs.

 

[Grover54]

Thanks guys! That's a great idea to follow the opposite end wing specs. I'm sure it's much easier to re-apply Monokote than tear down and redo a structural piece several times. I anticipated a Monokote problem so I already ran out and grabbed a roll of the Cub Yellow and Olive Drab from my local Hobby Store. Stay tuned!